USE OF THE REVISED UNIVERSAL SOIL LOSS EQUATION AND GIS TECHNIQUES TO MODEL SOIL EROSION RISK IN ROCKY MOUNTAIN NATIONAL PARK

Janke, Jason; Mallory, Dwight

The Revised Universal Soil Loss Equation (RUSLE) was used in conjunction with GIS raster modeling techniques to estimate potential soil erosion in Rocky Mountain National Park (ROMO). Currently, 6% of ROMO consists of soils with erosion rates greater than 5 tons/acre/year. The following regions have high erosion rates: 1) east of Long’s Peak; 2) along Stormy Peaks Pass Trail; 3) along the Continental Divide near the southern edge of the Park’s boundary; and 4) in the Hayden Lake area. Jim’s Grove Trail, the Alluvial Fan Trail, East Long’s Peak Trail, and Stormy Peaks Pass Trail have more than 30% of their extent underlain by highly erosive soils. Simulations were run to determine the effects of increased tree mortality from pine beetle kill on soil erosion rates. According to the post-pine beetle model, erosion rates greater than 5 tons/acre/year cover 33% of ROMO, a 28% increase from previous categorized high erosion areas. Bowen-Baker Gulch, Twin-Gem, Bear Lake Bypass, and Bierstadt Mountain Trails have more than 90% of their length underlain by highly erosive soils following the pine beetle disturbance. If a fire were to occur, soil erosion could enhance the frequency of debris flows and slides, especially during short, intense precipitation events. The methods employed in this study only identify high-risk areas of erosion, a useful management tool for narrowing sites from a larger geographic region; however, actual erosion rates should be verified in the field.